This read-write action attribute clears entries from the ComPort's Ethernet filter tables, with distinct options to flush the learned-MAC table, the EtherType filter table, or the IP filter table. It gives an operator a targeted way to clear out stale filter state (for example after swapping subscriber equipment) without having to reconfigure every filter from scratch. For example, after a subscriber replaces their PC, an operator would set stuEtherFiltFlushAction to flushMac so the STU forgets the old machine's MAC address and learns the new one cleanly.